Interactions of galaxies outside clusters and massive groups

Journal of Astrophysics and Astronomy

JASWANT K. YADAV^1²  XUELEI CHEN^2,3³ 

[1] Center of High Energy Physics, Peking University, Beijing 100871, China.^3;Department of Physics, Central University of Haryana, Mahendergarh, Haryana 123031, India.^1;National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012, China.^2

关键词: Galaxie;    sevolution;    galaxies;    interactions;    galaxies;    fundamental parameters;    galaxies;    general.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

We investigate the dependence of physical properties of galaxies on small- and large-scale density environment. The galaxy population consists of mainly passively evolving galaxies in comparatively lowdensity regions of Sloan Digital Sky Survey (SDSS). We adopt (i) local density, $\rho_{20}$, derived using adaptive smoothing kernel, (ii) projected distance, $r_p$, to the nearest neighbor galaxy and (iii) the morphology of the nearest neighbor galaxy as various definitions of environment parameters of every galaxy in our sample. In orderto detect long-range interaction effects, we group galaxy interactions into four cases depending on morphology of the target and neighbor galaxies. This study builds upon an earlier study by Park and Choi (2009) by including improved definitions of target and neighbor galaxies, thus enabling us to better understand the effect of “the nearest neighbor” interaction on the galaxy. We report that the impact of interaction on galaxy properties is detectable at least up to the pair separation corresponding to the virial radius of (the neighbor) galaxies. Thisturns out to be mostly between 210 and 360 $h^{-1}$ kpc for galaxies included in our study.We report that early type fraction for isolated galaxies with $r_p \ge r_{vir,nei}$ is almost ignorant of the background density and has a very weakdensity dependence for closed pairs. Star formation activity of a galaxy is found to be crucially dependent on neighbor galaxy morphology. We find star formation activity parameters and structure parameters of galaxies to be independent of the large-scale background density.We also exhibit that changing the absolute magnitude of the neighbor galaxies does not affect significantly the star formation activity of those target galaxies whose morphology and luminosities are fixed.

【 授权许可】

CC BY